This guide is derived and condensed from Danziger's Hypericum Cultivation Description. We highly recommend reading it in its entirety, as it contains essential growing information. Danziger is the breeder of our GypsophilaVeronica SkylerGlory Solidago, and Scoop Scabiosa

Common Name Hypericum (aka St. John's Wort)         
Genus  Hypericum
Species various 
Family Clusiaceae / Guttiferae 
Life Cycle  Can be annual or perennial, shrub or deciduous tree.
Tray Size  50 (Half Tray)
Plug Care
Harden off for the field, or transplant right away into a tunnel. If you cannot transplant, bump up to larger pots. During the first ten days after transplant (establishment stage), overhead irrigation should be used and can be supplemented with drip irrigation and fertilizer. 
Netting / Staking Support netting is recommended. 30% shade cloth can be used in summer to protect berries and foliage from discoloration. This may not be necessary.
Temperature Range Ideal temperature range is 75-80F daytime. 55-60F night. They are adaptable outside of this range.
Spacing 9"
Soil Preference All types of drained soils and on detached medias.
Day Length
Pinching Pinching to a minimum of 7-10 internodes
from the plant’s base (at least a month after planting), allowing growth of side stems. 
When to Plant Late spring or Early Fall
Harvesting Harvest when berries are ripe and colored. Cut back to just a couple of inches, to allow them to regrow.
Post Harvest Care
Diseases / Insects Rust can be an issue in very humid conditions.
Bailey's Notes

Danziger Hypericum Culture Guide